I would say it is indeed "primarily a 2-player game". Nevertheless it is principally possible to split up the command of both armies down to "one commander per corps".
The rulebook provides rules for teamplay (2-4 player per side) in which the players agree on a commander-in-chief and a rank order. By these rules communication is very limited to simulate the historical battlefield situation. The extra-rules for teamplay are optional of course and I can tell you by my personal experience that it is also a lot of fun just to split both armies in half and talk freely about what is to be done next.
The real problem is different: I find it difficult to find one further opponent willing to go through the steep learning curve with me and invest several evenings in getting used to the game system. Finding 3 or more at the same time... If that is no problem for you I envy you sooooo much! :)
I have a gaming group that is willing to try literally anything, and they have latched onto anything I present.
I have taught 4-5 first-timers Caylus, for example, in the last 6 months without a hitch, and everyone comes back for more.
I have been thinking a war-style game would be a good change of scenery, so i am just looking around at stuff I want to play!